Air-change system for a multi-storey building

ABSTRACT

A ventilation system for a multi-storey building, which system comprises a ventilation apparatus mounted on a roof and provided with fans for generating an inlet air flow and a distributing channel for supplying the inlet air flow to various intermediate levels of the building. A service shaft of the building serves as an inlet air flow channel, which shaft forms a flow path for the inlet-air flow directed from the fans downwards, whereby the service shaft has deflecting means for passing a part of the air flow to each intermediate level of the building.

BACKGROUND OF THE INVENTION

This invention relates to a ventilation system for a multi-storeybuilding, which system comprises

an apparatus mounted on the roof of the building with fans forgenerating an inlet air flow

and

a distributing channel for supplying the inlet air flow to variousintermediate levels of the building.

In high buildings, in which indoor air is warmer than outdoor air, apressure difference arises between the upper and lower part of thebuilding. Since buildings are not airtight, air leaks through theconstructions from the upper part of the building outwards and from thelower part inwards. Inside the building the air flows from belowupwards.

Because of leaks, the lower part of the building is cold and draughtoften appears therein. In the upper part it is easily hot and if thehumidity of the indoor air is clearly higher than the humidity of theoutdoor air, leaking air may condense to water in the constructions.Impurities are spread by the internal air flows of the building.

These drawbacks can be prevented by constructing the intermediate levelsas airtight as possible in the building. In residential and officebuildings, for instance, the building has thus been successfully dividedinto parts independent of each other, within which the effects of thepressure difference can be eliminated by conventional air-conditioningtechniques thanks to the slightness of the pressure difference.

In industrial buildings again, in which there are many big passages forproduction equipment, manholes holes and service shafts etc. through thelevels, it would be extremely expensive and difficult, if not directlyimpossible, to build airtight levels.

If there are no intermediate levels in the building, temperaturedifferences between the upper and lower part of the building can beequalized by means of strong air jets, which extend from the vicinity ofthe roof nearly to the plane of the floor, bring along air from theupper part of the building and mix it effectively. Such a system isknown from Finnish Patent no. 56 714.

Such a system cannot be used in multi-storey buildings, even though theintermediate levels were air permeable, such as plane grates, becauseareas with strong air jets are not suited for working places.

If there are only a few intermediate levels, pressure and temperaturedifferences have been equalized by means of axial-flow fans mounted onthe levels, which fans blow air from an upper level downwards. Still,they take up valuable floor space, cause noise problems, consumeelectric power and are relatively ineffective with respect to balancingthe temperature, because the air from the fan is in a strong rotatingmotion. The air does not flow as a jet to a lower level, but spreadsalong the ceiling of the lower level, whereby no mixing to balancetemperatures occurs.

So, temperature and pressure differences in high multi-storey buildingsgenerally tend to be reduced in such a way that a maximum part of theventilation air is passed through channels to the lower part of thebuilding and only a minimum air flow necessary for the air quality tothe upper part. Pressure differences can thus be slightly equalized,which has some effect on leaks and temperature differences, but the airflow required for the ventilation generally is quite insufficient for aneffective pressure balancing. The channels take up space in thebuilding, to build them causes costs and to locate them in the buildingis difficult. An effective air distribution by means of conventional airdistributing devices to often wide levels seldom succeeds withoutdistributing channels, which additionally increases the costs. A problemof its own is caused by the regulation. A pressure and temperaturedifference in a building depends on the temperature difference betweenthe indoor and outdoor air, according to which it should be possible toregulate the ratio of the inlet air flows of the upper and lower part ofthe building. This is not possible in practice because of the high costsdue to the great amount of both air distributing and regulating devices.The result of the above is that e.g. the lower part of the building issubjected to underpressure in winter and to overpressure in summer. Thepressure ratios are opposite in the upper part and the air quality isoften bad.

SUMMARY OF THE INVENTION

The object of this invention is to provide a ventilation system avoidingthe above drawbacks and enabling a decrease of the costs and the need ofspace of the ventilation apparatus, an improvement of the airdistribution and so of the air quality as well as an improvement of theadjustability of the system. This object is achieved by means of aventilation system according to the invention, which system ischaracterized in

that a service shaft of the building or a similar space extendingvertically through the building and opening to the intermediate levelsserves as an inlet air flow channel, forming a flow path for the inletair flow directed from the fans downwards,

and

that the service shaft has deflecting means for passing a part of theair flow to each intermediate level of the building.

The invention is based on the idea that a service shaft of the buildingis used as an inlet air channel and that the ventilation apparatus ispositioned up on the service shaft in order that the air can be blown byfans belonging to the ventilation apparatus anyhow as a big and strongair jet along the service shaft down into the building. Then the serviceshaft acts as a channel for the inlet air and no other channel isneeded. This decreases the costs considerably, because the costs ofbuilding a special inlet air channel and the costs of the necessarybuilding space required are omitted.

In industrial buildings, such as boiler plants, there is generally avertical service shaft covered by easily removable grates, which shaftextends through the building. Because it shall be possible any time tolift machines to be maintained or repaired, spare parts, machines andaccessories necessary for repairs, etc. through the shaft to variouslevels, no working positions, stocks or other functions are placed atthe service shaft. In buildings like this, as in most other buildings,the ventilation apparatus is generally positioned on the roof of thebuilding for reasons of air quality, effective space utilization etc. Torealize the invention, the ventilation apparatus and the service shaftare just to be arranged in such a manner with respect to each other thatthe service shaft replaces the conventional separate channel systemrequired for the inlet air flow, through which system the inlet air ispassed to the various storeys of the building.

The fans of a boiler plant, for instance, are generally axial-flow fans,from which the air starts in a strong rotating motion. When enteringinto free space the air jet would therefore spread quickly sidewards andthe Jet would be quickly retarded and would not extend very fardownwards.

The influence of the rotating motion can be considerably reduced if theservice shaft is located in a corner of the building, in which case thewalls prevent the flow from widening in two directions. Moreover, thejet extends considerably farther under the influence of the so-calledCoanda phenomenon: the jet is subjected to an underpressure of the sizeof about the dynamic pressure compared to the surrounding air so thatthe jet is kept together by the pressure difference. In addition, amixing of the surrounding air, which retards the jet most strongly, isprevented in two directions.

If the building in question is high, a turbulent air flow can preventthe air jet from extending down to the lower part of a deep serviceshaft. The air jet could be straightened by means of a set of guidevanes, the costs of which are, however, disproportionate because of thecomplicated shape, nearly as high as those of a fan without a motor. Arotating motion can still be stopped practically without costs in a verysimple manner.

An embodiment of the system according to the invention is characterizedin that the ventilation apparatus comprises at least two axial-flow fansmounted adjacent to each other and generating at least two parallelturbulent flows braking each other and forming an inlet air flowdirected downwards. The turbulent flows from the fans brake then eachother effectively. In addition, the moment of the quantity of motion ofeach whirl is considerably smaller than that of one big, in the same wayas the diameter of the whirl, so that the rotating motion is retardedmore quickly when the whirl is widening. The costs rise perhaps alittle, but it is compensated for by an increase of the operationalreliability. Even if one fan gets broken, the plant continues to operatewith reduced effect.

A preferable embodiment of the system according to the invention ischaracterized in that an air flow directing unit consisting of fans anda directing device is mounted at least at one intermediate level in theservice shaft to guide the inlet air flow in the direction of theservice shaft. By means of this construction, it is possible to controlthe air distribution to the various levels of the building in a suitablemanner, as well as the air distribution over the whole area of the levelequally or in a desired manner.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will below be described more accurately referring to theenclosed drawings, in which

FIG. 1 shows schematically a building and a ventilation system mountedtherein, which conforms to an embodiment of the invention,

FIGS. 2 and 3 show a fan unit of a ventilation apparatus from the sideand a cross-section of an air flow generated, respectively,

FIGS. 4 and 5 show a part of a service shaft of the building with airflow deflecting means from the side in two different regulatingpositions, and

FIG. 6 shows a part of the service shaft provided with distributingnozzles from the side.

DESCRIPTION

FIG. 1 of the drawings shows a multi-storey building 1, in one corner ofwhich there is a vertical service shaft 3 extending through variousstoreys (intermediate levels) 2 of the building from top to bottom. Aventilation apparatus 4 comprising a fan unit 5 is mounted on the roofof the building. The service shaft can be covered by easily removablegrates at the storeys.

The fan unit comprises in this example four axial-flow fans 6 mountedsymmetrically adjacent to each other. The fans suck outdoor air Athrough treatment devices of the ventilation apparatus and blow an inletair flow B directed downwards into the service shaft.

The fans generate four parallel turbulent flows B' directed downwardsand braking each other, which together form the inlet air flow B, asshown in FIG. 3.

On the outlet side of each fan is mounted an equalizing chamber 7, inwhich a through channel is divided by means of separation walls 8 intosmall flow channels 9, the length of which is great compared with thebreadth. The separation walls are made of a sound-absorbing material sothat the equalizing chamber serves as a sound dampener.

Nozzles 10 generating support jets C directed downwards are mounted atsome storeys at the edges of the service shaft, which nozzles securethat the inlet air flow B is kept together and in a right direction. Invery high buildings the air flow can be brought down by placing a unitconsisting of fans and equalizing chambers, similar to the one placed onthe roof, also on one intermediate level or on several levels.

According to experience, the air jet can be caused to extend from thehighest storey to the lowest in a building higher than 70 meters bymeans of the system described. The air flow moving with the jet ismultiple compared to the inlet air flow, because the high-speed air ofthe Jet brings along surrounding air from the upper part of thebuilding. Pressure balancing is thus very effective.

Deflecting means 11 are mounted at each storey in the service shaft,which means at a storey deflect a part of the inlet air flow to the areaof the storey. The deflecting means are in this embodiment formed ofplates 12 pivotally mounted in bearings, which plates extend into theair flow. In winter the plates are in a vertical position in the upperstoreys, whereby only a small part D of the air flow is deflected to thehighest storeys, as presented in FIG. 4. In summer the plates are turnedto a horizontal position indicated by broken lines, whereby a greaterpart D of the air jet is deflected to the highest storeys, as presentedin FIG. 5. In the lower part of the building the function is oppositeand in the middle part the plates can mostly be fixed. The control ofthe position can take place on the basis of the outdoor temperature.

Pressure ratios between the storeys can thus be controlled relativelyexactly without increasing the air flow of the fans.

A row of horizontally blowing high-speed nozzles 13 is mounted at eachstorey at the edge of the service shaft, which nozzles draw air E fromthe vertical flow and blow it to the level, as shown in FIG. 6. By thechoice of nozzle size, air speed therein, blowing direction and suitablelocation, the air can be caused to spread to the levels in a desiredmanner. The influence of the outdoor temperature on the pressure ratiosof the building can be eliminated by adjusting the impulse of thenozzles in manners described in Finnish Patent 66 484, for instance.

The air flow of the nozzles is small compared to the air flow impelledby the nozzles, so that the power consumption is moderate. They can bepositioned at the edge of the service shaft, and thus, they do notimpede the use of the shaft.

The description above is only intended to illustrate the idea of theinvention. As to the details, the system of the invention can varywithin the scope of the claims. The elements described can be combinedin many different ways and systems with slightly different propertiescan be provided. The invention can also be applied to anair-conditioning plant. Instead of the service shaft, some other freespace of the building extending vertically through it and being inconnection with the intermediate levels can be used.

We claim:
 1. A ventilation system for a multi-storey building havingintermediate levels and a roof, said system comprising:a ventilationapparatus mounted on the roof of the building with fans for generating adirected inlet air flow; and a ductless service shaft extendingvertically through the building which is formed by vertically spacedopening in each level of the building, said service shaft forming a flowpath directed downwards from the fans wherein said service shaft permitssurrounding air to be brought along from upper ones of said intermediatelevels to lower ones of said intermediate levels, and wherein saidservice shaft serving as an inlet air flow channel having deflectingmeans for passing a part of the air flow to each of said intermediatelevels of said building.
 2. A system according to claim 1, wherein theservice shaft is located in a corner of the building.
 3. A systemaccording to claim 1 wherein the ventilation apparatus comprises atleast two axial-flow fans mounted adjacent to each other, which generateat least two parallel turbulent flows braking each other and forming theinlet air flow directed downwards.
 4. A system according to claim 3wherein additionally directing means for the inlet air flow are mountedafter the fans to direct the inlet air flow in the direction of theservice shaft.
 5. A system according to claim 4 wherein saidadditionally directing means is a support jet mounted at least at oneintermediate level in the service shaft to direct the inlet air flow inthe direction of the service shaft.
 6. A system according to claim 1wherein the deflecting means comprises deflecting plates mounted atdesired intermediate levels in the service shaft, said deflecting platesbeing adjustable between a vertical position and a horizontal positionsuch that the positions of said deflecting plates control the amount ofair flow entering said intermediate levels.
 7. A system according toclaim 1 wherein the deflecting means are formed by distributing nozzlesparallel with the intermediate levels and mounted at desiredintermediate levels at the edge of the service shaft, which nozzles takeair from the inlet air flow and blow it over the intermediate level. 8.A system according to claim 1 comprising a flow equalizing part mountedin the service shaft after the fans, which flow equalizing part forms anumber of adjacent flow channels separated by separation walls to dampenthe turbulence of the inlet air flow and to equalize the flow.
 9. Asystem according to claim 8 wherein the separation walls comprise asound-absorbing material.
 10. A system according to claim 4 wherein thedirecting means are formed by nozzles mounted at a desired intermediatelevel at the edge of the service shaft, which nozzles generate downwardsblowing support jets parallel with the service shaft.
 11. A systemaccording to claim 2, wherein the ventilation apparatus comprises atleast two axial-flow fans mounted adjacent to each other, which generateat least two parallel turbulent flows braking each other and forming theinlet air flow directed downwards.